Tetravalent cerium carbene complexes

Abstract

The tetravalent organometallic cerium complex [CeL4] is readily accessible from the oxidation of the trivalent [CeL3], L=a bidentate N-heterocyclic carbene alkoxide ligand, [C{(NPri)CHCHN}CH2CMe2O]. The [CeL4] complex should behave like the [UL4] analogue, but the two complexes show significantly different structures, highlighting the differences between 4f and 5f metals.

Functionalised Saturated‐Backbone Carbene Ligands: Yttrium and Uranyl Alkoxy–Carbene Complexes and Bicyclic Carbene–Alcohol Adducts

“…[22] We have previously reported syntheses of unsaturated alcohol-carbene ligands, [23,24] and their use in copper-catalysed asymmetric conjugate addition, [25] lactide polymerisation, [26] and Group 4 [27] and f-block organometallic chemistry. [28,29] We, like others, have found that the acidity of the protons of the carbene heterocyclic backbone can lead to unanticipated, and sometimes unwanted, ligand rearrangements. Herein we report a modular synthesis of bidentate alkoxy-functionalised saturated NHC ligands and the first examples of early metal saturated carbene complexes; adducts of Y III and the uranyl dication.…”

Covalency in CeIV and UIV Halide and N‐Heterocyclic Carbene Bonds

“…[32][33][34][35][36][37] The first Ce IV cyclopentadienyl complex [38] was the tris(cyclopentadienyl)-supported Ce IV isopropoxide (D) reported by Marks et al, [39] closely followed by the crystallographically characterised tert-butoxide analogue reported by Evans et al [40] We have demonstrated the synthesis of [CeL 4 ] (L= OCMe 2 CH 2 (CNCHCHNiPr); E). [41,42] The Ce IV ion is supported by two bound and two unbound unsaturated backbone NHC ligands and is the only example of a Ce IV À C two-electron s bond.…”

Synthesis and Characterization of Cerium(IV) Metallocenes

“…The synthesis of Ce(IV) organometallic complexes, however, is limited by the lack of available starting materials and this has constrained the growth and development of traditional organometallic chemistry and reactivity using this high-oxidation state lanthanide [17]. Two main approaches exist as entry points into Ce(IV) chemistry; the oxidation of Ce(III) compounds and the use of materials such as Ce(OPr [22]. Benzoquinone was also used effectively to oxidize [Ce{N(SiMe3)2}3] to form the new cerium(IV) silylamide complex [Ce{N(SiMe3)2}3(bda)0.5]2 (bda = 1,4-benzenediolato) [23].…”